The inventive concept relates to a data storage device, and more particularly to a magnetic racetrack memory device that uses transfer of magnetic domains and magnetic domain walls.
Hard disk drives (HDDs) are data storage devices that allow the storage of “write data” on a rotating magnetic disk (or similar magnetic recording medium) via operation of a read/write head positioned over the magnetic recording medium. Upon subsequent demand, stored data may be retrieved as “read data” from the magnetic recording medium using the read/write head. Contemporary HDDs are high-density, nonvolatile data storage devices, and are generally implemented using a number of moving mechanical components and related electro-mechanical circuits. The increasing demand for denser data storage together with the relatively delicate nature of the moving mechanical components forming an HDD lead inexorably to problems associated with deterioration of mobility, accuracy of positioning and general reliability. Further, manufacturing complexity and corresponding costs, as well as concerns over power consumption and noise generation have negative competitive implications for conventional HDDs.
Accordingly, a number of recent development efforts have been directed to replacement data storage devices capable of providing commensurate data storage capabilities, but without all the complex, moving mechanical systems. One possible replacement device commonly referred to as the “magnetic racetrack memory device” uses a physics principle that recognizes that magnetic domains and magnetic domain walls move within a magnetic material (i.e., a magnetic body). One example of a known magnetic racetrack memory device is disclosed in published U.S. Patent Application 2004/0252538.
In general, conventional magnetic racetrack memory devices include a magnetic body constructed in a linear magnetic track shape of predetermined length. The magnetic track includes a plurality of magnetic domains which are partitioned by magnetic domain walls.
Unfortunately, in a conventional magnetic racetrack memory device, data cannot be written to an area corresponding to at least half of the magnetic track. That is, at least half of the magnetic track must be set aside as a buffer area. In the absence of this buffer area (although magnetic domains need to pass below a reading device in order to read information from the magnetic domains), some of the magnetic domains are moved outside an end of the magnetic track and corresponding data is lost.